putting a vapor barrier or tyvek under stone

hey DIY, looking for some professional opinions, i have a 8x14 deck that is about 12inchs above the ground the deck boards have been removed because of some rot that was visible, now all that is there is framing and is also showing signs of rot, i am seeing some rot under the sill, looks like a 1x4 or 1x5 that is under the sill and on top of the cinder blocks, this runs the width of the deck about 8ft, it is very much rotted in some spots, how can this be removed without getting to involved? i also had water leaking thru the foundation in this area, so i was thinking on putting down a vapor barrier and crushed stone for drainage purposes, lowes said i could use tyvek because one side is waterproof while the other side will breathe. i am in phippsburg maine for the week at my second home and would like this straightened out before i leave this weekend.

putting a vapor barrier or tyvek under stone

Without seeing pics of the situation, I wouldn't know. Is the house on a slope? Is the wall poured concrete, CMU or stone? Is the wall just damp or is water actually coming through?

If it's water coming through, you obviously need some form of tanking, whether internal or external. Retro-fitted external tanking, as you suggested, may not necessarily work, as you can get leakage through the wall/floor joint. If you do consider that, something more substantial than Tyvek would be needed.

Internal tanking and drainage is usually best, though expensive. I suppose a lot depends on what you want to use the space for.

putting a vapor barrier or tyvek under stone

there is a door leading out to the deck, the threshold has rot on the outside, i am assuming from water splashing up off the decking when it is raining, this area is where water can find it's way down the foundation, the deck and ground are level, no slope, some of the foundation is cinder block [newer], below is older stone wall[ 1870's], in maine all basements have some dampness, there was no flashing under threshold so this needs to be corrected,the cinderblock cavity's are seen from the outside on some spot's, this needs to be filled with concrete i would think. the crushed stone i am thinking will help with drainage, the vapor barrier was a afterthought.

putting a vapor barrier or tyvek under stone

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putting a vapor barrier or tyvek under stone

yes lead flashing was used on one side 14ft, but not under doorway wall 8ft, thanks for the photo, my siding is old 1800's wood, still in good shape though, the floor joist [stringers] run the lenght of deck, but when they installed them they were notched out and put on top of the cinderblocks, and then put a 4x4 between each joist, inside the wall in the basement is a full lenght sill board though, this was a addition that was done in the 20's, the stringers are 20inchs apart, i was thinking of running the joist in the other direction to make the floor stronger. maybe this is a better idea, any thoughts? is copper flashing a better choice than lead flashing?